Air-pressure railway brake



J. RlHosEK Er'AL AIR PRESSURE RAILWAY BRAKE Jan. 5 1926. 1,568,533

'Filed May 20, 1925 4 sheets-sheet 41 Jan. 5 1926.

. 1,568,533 J. mHosE-K Er Al.

AIR PRESSURE RAILWAY BRAKE Filed may 2o, 1925 4 Sheets-sheet 2 Jan. 5 1926.

J. RIHOSEK ET Al.

AIR PRESSURE RAILWAY BRAKE Filed May 20, -1925 4 Sheets-Sheet .5

W6 s U9 A /vD gaa/@fan Jan. 5 1926.

J. RIHOSEK ET AL AIR PRESSURE RAILWAY BRAKE Filed May`20, 1925 v4 sheets-sheet 4 recogen UNITED STATES PATENT OFFICE.

JOHANN RIHOSEK, F VIENNA, AND RICHARD LUDWIG IIEUCHTER, 0F WEIDLIN- GAU-HADERSDORF, AUSTRIA, ASSIGNORS TO THE FIRM GEBRDER HARDY, MASCHINENFABRIK UND lGIESSEREI A. G., OF VIENNA, AUSTRIA.

AIR-PRESSURE RAILWAY BRAKE.

Application filed May 20, 1925.

To all whom t may concern.'

Be it known that JOHANN RIHosEK and RICHARD LUDWIG LEUCHTER, citizens of the Republic of Austria, residing at Vienna and Wei-dlingau-Hadersdorf, Austria, respectively, have invented certain new and i seful Improvements in Air-Pressure Railway Brakes, of which the following is a specification.

Our invention relates to air pressure brakes for railways and more particularly to single chamber air pressure brakes. While the brake controlling valves heretofore used in such brakes permit the brakes to be applied step by step, they do not permit the brakes to be released step by step. The latter fact constitutes a serious drawback as more particularly in mountain railways it is highly desirable to release the brakes step by step for taking long inclines with certainty.

The object of our invention is to remove this drawback and with this object in view our invention consists in that the controlling element controlling the escape of air under pressure from the brake control valve is connected with an actuating piston being on one side permanently under the action of the pressure in the train pipe and on the other side under the action of a spring or weight acting in the opposite direction, a connection between the two sides of the piston controlled by the said controlling element bringing about while the pressure in the train pipe is increasing from time to time an equalization of pressures on the 0pposite sides of the piston and thereby a movement of the piston and the controlling element connected thereto alternately shutting off and opening the escape of the air under pressure from the brake control valve.

This operation is continued whether the increase of pressure in the train pipe is continuous and slow or whether it is intermittent. In this way a step by step release of the brakes is obtained. When the pressure in the brake cylinder has sunk to a predetermined value the controlling element permits automatically any air under pressure to escape from the brake cylinder.

In the drawings Figs. 1, 2 and 3 show longitudinal sections of a constructional form of the present invention in various positions. 1

Fig. 4 shows a modification thereof,

Figs. 5, 6, 7 and 8 show a modified con- Seral N-o. 31,665.

structional form of the controlling element in different positions.

Figs. 9 and 10 are views similar to Figs. 1 to 3 of a simplified constructional form of our invention showing the slide valve 1n two different positions. Figs. 11 and 12 show a detail thereof in section in two dierent positions.

In a cylinder 1, Figs. 1 to 3 there works a piston 2, one end of the cylinder being permanently connected to the atmosphere by an opening 4 and the other end to the brake cylinder not shown. The rod 5 of the piston 2 extends air tight into a second cylinder 6 in which works a piston 7 with a slide valve 17 and is acted upon by a spring 18 or by gravity (Fig. 4) or by both. One end of the cylinder 6 is permanently connected by a pipe 8 to the train pipe and is connected wih the other side of the piston by a channel 13 in which an automatic. valve 14 is provided Which closes whenever the pressure in the pipe 8 is in excess. Furthermore from the same end of the cylinder 6 a channel 12 leads to a port 26 in the seat of the slide valve 17. Another port in the same seat is connected by a channel 10 with a pipe 9 leading to the exhaust opening of the brake control valve not shown of known construction and a third port of the valve seat is in permanently open connection with the atmosphere by a channel 11.

In the position of rest when the brakes are released there is atmospheric pressure in the brake cylinder and also in the space of the cylinder 1 connected therewith while in both spaces of the cylinder 6 there is the pressure existing in the train pipe (about tive atmospheres). Owing to the equality of pressures on both sides of the two pistons 2 and 7 the latter twotogether with the slide valve 17 are forced into an eXtreme position (according to Fig. 1 the left one) by the spring 18 or by gravity or by both in which eXtreme position the two sides of the piston 7 are connected with each other by the channel 12 in the slide valve seat and by the channel 20 in the slide valve, while the pipe 9 is connected to the atmosphere by the channels 10, 11 in the slide valve seat and the channels 24, 21, 23 in the slide valve.

When the brakes have to be applied the pressure in the train pipe is reduced and thereby the brake control valve is brought into such a osition that it causes air under pressure to ow from t-he auxiliar container into the brake cylinder and thereby also to one side (as shown in Fig. l the lett one) ot' the piston 2. The piston 2 is moved to the right and moves in turn the piston 7 together with the slide valve 17, air under pressure passing from the right hand side of the piston 7 to its left hand side through the automatic valve 14 and the channel 13. Thus the parts come into the position shown in Fig. 2 in which the slide valve 17 closes all ports in its seat and the brakes are applied With a brake shoe pressure corresponding to the reduction ot pressure in the train pipe. On a further reduction ot pressure in the train pipe it'or increasing the brake shoe pressure nothing is changed in the braking position of the parts shown in Fig.V 2.

It' now for releasing the brakes the pres sure in the train pipe is again increased, the piston 2 remains in its extreme right hand position shown in Fig. 2, but the piston 7 of the cylinder G is moved stili further to the right into the position shown in Fig. 3 by the increased pressure in the train pipe acting on its lett hand side as this pressure cannot be transmitted to the right hand side of this piston in the position shown in Fig. 2. Thereby the connection between the spaces on opposite. sides ot the piston 7 ot' the cyl inder 6 is again established by the channel l2 in the slide valve seat and the channel 19 in the slide valve and the pressure on both sides of the piston 7 are equalized after a longer or shorter time according to the sectional area of these channels. The pipe 9 is connected to the atmosphere by the channels lO, ll of the slide valve seat and the channels 22, 2l, 24 of the atmosphere. their the pressures are equalized the slning 1S pushes the piston 7 and the slide valve 17 back into the position shown in Fig. 2 Whereby the release of the brakes is interrupted the escape of air under pressure from the brake cylinder past the brake control valve and the pipe 9 lbeing shut ofi". The rod 5 of the piston 2 then serves as a stroke limiting stop for the piston 7. lVhen the pressure in the train pipe further increases continuously, the operation described is repeated after some time. But the step by step release ot the brakes may be O'overned at will by increasing the pressure in the train pipe intermittently making the intervals between any two successive increases of pressure suniciently long.

Whenever in releasing the brakes step by step the pressure in the brake cylinder has sunk so Jfar that in the position of the parts shown in Fig. 2 the spring 18 overcomes the brake cylinder pressure acting on the piston 2, the parts are returned into the position shown in Fig. 17 the remainder of air under pressure contained in the brake cylinder escaping to the atmosphere through the brake control pipe 9 and the channels l0, 24, 2l7 23 and then the brakes are fully released.

The change of the position shown in Fig. 2 into that shown in Fig. 3 may be somewhat accelerated by causing the channel 18 to enter into the pipe 8 in the form of a suction nozzle l5 so that when air under pressure flows ,trom the train pipe to the left hand side oi the piston 7 some air under pressure is drawn ott the right hand side ot' this piston.

Instead ot locating the cylinders l and 6 in line and horizontally as shown in Figs. l to 3 they may also be arranged vertically7 the one above the other as shown in Fig-...LL in which gravity can act on the piston and slide valve in the same sense as the spring 18 in Figs. l to 3.

ln the constructional form shown in Figs. l to it may happen under certain conditions, more particularly when the internal volume ot the cylinder (i is comparatively small7 that the compressions and expansions of the air contained in the cylinder due to the movements oit the piston 7 retard the movements ot the piston to such an extent that the desired controlling movement ot the slide valve is not brought about. ln order to do away With this possibility the slide valve may be constructed as shown in Figs. 5 to S. As will be seen the channel l2 is provided .in this constructiona-l torni with a branch channel 82 ending in a port of the slide valve seat While for the channel 20 tivo channels 28, 30 are substituted which lead to a recess in the slide valve into which ena projection 29 on the slide valve rod 1G. This projection acts as a double seat valve closing according to the .direction ot n'iovement oit' the slide valve rod the end of the one or the other channels 28 or 30. rFhe end of the channel 30 next to the seat of the slide valve leads to a recess 25 in the slide valve, such recess extending to both sides of a transverse partition. Furthermore a channel 26 is provided leading from a. part between the ports of the channels l2 and 32 o't the slide valve seat and ending in the channel l1 connected to the atmosphere.

lVhen at rest the slide valve is in the position shown in Fig. 5 in which the projection 29 closes the port ot the channel 28 While the channels 2O and l2 connect the spaces on both sides ot the piston. On applying the brakes the slide valve comes into the position shown in Fig. in Which the projection 29 closes the port ot the channel 30. On applying the brakes there is no other difference over the dietriliution by the slide valve as compared with the constructional torni shown in Figs. 1 to 3. It, however, on relOO leasing the brakes it is moved into the position shown in Fig. 7, the channel 28 moves over the part of the channel 26 in the slide valve seat so that the interior of the cylinder G is connected for a short time with the atmosphere whereby a suiiicient quantity of air is permitted to escape for avoiding a compression on the right hand side of the piston 7 which would interfere with the movement of the slide valve.

When equalization of pressures on both sides or' the piston and the slide valve moves under the action of the spring from the position shown in Fig. 7 into the position shown in Fig. 8 the two sides of the piston remain connected by the channels 30 and 12 owing to the arrangement ot the recess 25 until the transverse partition 27 covers the port of the channel 12in the slide valve seat. Therefore during this part of the movement of the slide valve a sufficient quantity of air can How from the left hand side to the right hand side of the piston 7 through the channels 12 and 8O that an expansion on the right hand side of the piston that might interfere with the movement of the slide valve is avoided. As the step by step releasing of the brakes continues the channel 28 moves each time over the port of the channel 26 so that also in the following steps ot releasing the brakes no appreciable compression can be set up in the movements of the piston. Otherwise this arrangement of the slide valve operates in exactly the same manner as fully described with reference to Figs. 1 to 3 of the drawing.

In the constructional form hereinbefore described it may happen under particularly unfavorable conditions that the air under pressure escaping from the brake control valve causes the brakes to be applied. In order to obviate this deficiency and moreover to enable the brakes of a vehicle or part of the train separated from the locomotive to be readily released and furthermore. to simplify the constructional form above described, we provide a valve interposed between the pipe leading to the brake control valve and a port leading to the atmosphere, and so arrange such valve that it establishes connection between the said pipe and port when the pressure in the pipe exceeds a predetermined limit. This valve may be combined with a double seat valve having one of its seats in the space above the first named valve while its other seat is open to the atmosphere.

This constructional form is illustrated in Figs. 9 to 12.

The piston 7 works in the casing 6 and is rigidly connected with the controlling element constructed as a slide valve 17. The

spaces on the two sides of the piston are connected with each other on the one hand by a channel 12 and on the other hand by a channel 13 in which an automatic valve 14 is arranged, which opens whenever the air pressure on that side of the piston 7 on which directly acts the spring 18 is in excess ot' the air pressure acting on the opposite side oi the piston 7. rllhe interior of the casing 6 is in permanently open connection with the train pipe not shown by a pipe 8 and the train pipe pressure acts on the piston 7 in opposition to the spring 18. In the slide valve seat there are besides the port connected to the channel 12 two ports ot which the one is connected to a channel 11 leading to the atmosphere and the other to a channel 10 leading to the pipe 9 connected with the brake control valve. So far the constructional form shown in Figs. 9 and 10 is substantially the same as that shown in Figs. 1 to 8.

In the slide valve there is provided a re cess l1() which in one position oii the slide valve establishes communication between the channels 10, 11 and at the same time opens the port o1 the channel 12.

IVhen the brake is out oi operation and the brake cylinder, theI train pipe and the auxiliary reservoir contain only air under atmospheric pressure, the spring 18 causes the parts to occupy the position shown in Fig. 9 in which the channels 10, 11 and 12 are shut off by the slide valve 17. Iii' the brakes are made ready for application by admitting air under pressure into the train pipe and the auxiliary reservoir, the air under pressure entering through the pipe 8 drives the piston 7 against the action oit' the spring 18 to the left hand side ot' Fig. 9 until it strikes against the cushioned stationary seat 41 Fig. 10, the port of the channel 12 in the slide valve seat being uncovered and the channels 10 and 1.1 being connected with each other by the recess 10 oi the slide valve. In this position of the parts air u nder pressure flows from the right hand side to the left hand side of the piston 7 through the channel 12 in which a contracted part 42 is provided which retards equalization oit' pressures on the opposite sides or' the piston. As soon as equalization ot' pressures has taken place the piston 7 and the slide valve 17 are returned by the action of the spring 18 into the position shown in Fig. 9.

Vhen the. air pressure in the train pipe is reduced for the purpose of applying the brakes, the pressure on right hand side of the piston 7 is likewise reduced and thereby the automatic valve 14 is opened for again equalizing the pressure on both sides of the piston. The position ot the other parts remains unaltered.

When tor releasing the brakes the air pressure in the train pipe is increased the piston 7 is Jforced again into the position shown in Fig. 9 by the excess of pressure on the right hand side ot the piston 7 and at the same time the brake cylinder is connected in the usual way with the pipe 9 by means ot the brake control valve. Air under pressure escapes 'from the brake cylinder closing the valve 44 through the pipe 9, channel l0, recess 4() in the slide valve and channel ll into the atmosphere, until the pressures on both sides ot' the piston are equalized whereby the piston 7 and the slide valve i7 are returned into the position Fig. 9. Thus the first step ot' thc release ot the brakes is accomplished. This operation is repeated when the pressure in the train pipe is again increased.

Between the pipe 9 and the channel l0 we interpose according to our invention an opening 4() leading to the atmosphere and a valve acted upon by a spring 45, the latter being so selected that it keeps open the valve 44 and therefore also the connection between the pipe 9 and the openingl 46 leading to the atmosphere as long as the pressure in the pipe 9 does not exceed a predetermined limit. 'lhus when the brakes are iully released any air under pressure leaking` into this brake cylinder escapes through the brake control valve and the pipe 9 to the atmosphere, whereby an accidental application of the brakes yis avoided. Vhen the brakes are released that is to say in the position ot' the parts shown in Fig. 9 the pressure in the pipe 9 is sutlicient to close the valve 44 against the action ot the spring 45.

V lf it is desired to release the brakes of a vehicle or part oit a train separated from the locomotive and with the brake control valve in the release position it is only necessary to open the valve 44 by means of the hand lever 4T whereupon the air under pressure escapes :from the brake cylinder. But in this case the hand lever 47 must be maintained in thc position in which it keeps open the valve 44, until all air under pressure has escaped 'from the brake cylinder. yl'his inconvenience can be obviated by intcrposing, as shown in Figs. ll and l2, between the pipe 9 and the valve 44 a double scat valve 48 the top seat ot' which admits the air under pressure from the pipe 9 to the valve 44 while the bottom seat 50 ot the valve 47 leads directly to the atmosphere.

Normally the valve 4S rests on the bottom seat 50 and does not affect at all the operation or" the valve 44 (Fig. l1). If, however', the hand lever 49 is operated to raise both valves 44 and 48 simultaneously, as shown in Fig. 12 so that the valve 48 comes against its upper seat, all air under pressure escapes at once from the small space above the valve 48 through the opening 46 while the valve 48 is maintained in its raised position by the air under pressure escaping` trom the brake cylinder through the bottom seat 50 until the brakes are fully released. Conse- Meanies qucntly itis not necessary to hold the valves 44 and 48 by the hand lever 49 in their upper position,

'lhus the present arrangement provides l'or a convenient release ot the brakes of unconpled vehicles.

The piston 7 and the slide valve 17 may be operated by gravity or by gravity and a .spring instead of by the spring 18 alone.

What we claim is:

1. In a single chamber air pressure valve the combination ot a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing, whereby one side ot' the piston is constantly under the action of the train pipe air pressure, means permanently .acting with a snlistantially constant force on such piston in opposition to the train pipe air pressure, a brake control valve and a controlling elenient rnieratively connected to the said piston and adapted to control the connection between the escape side of the said brake control valve and the atmosphere and simultaneously a connection between the two sides ot the said piston.

ln a single chamber air pressure valve the combination. oi' a train pipe, a casing, a piston working in such casing, a permanent winnecton `from the train pipe to the casing, hereby one side of the piston is constantly under the action of the train pipe air pressure. means permanently acting with a substantially constant force on such piston in opposition to the train pipe air pressure, a brake control valve, a slide valve connected to the said piston and provided with ports and channels, a seat for such slide valve likewise provided with ports and three channels, one ot the latter being permanently connected to the atmosphere, the second bcing permanently connected to the escape side oit the brake control valve and the third channel being permanently connected to the side of the said piston opposite to the slide valve, such slide valve being adapted to close and open the third ot' the said channels and at the same time to break and establish respectively the connection between the first and the second orf the said three channels in the said slide valve seat.

$3. In a single chamber air pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing whereby one side of the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant force on such piston in opposition to the train pipe air pressure, a brake control valve, and a controlling element operatively connected to the said piston and adapted to control the connection between the escape side of the said brake control valve and the atmosphere and simultaneously a connection between the two sides of the said piston and a channel in the casing provided with an automatic valve adapted to open whenever the pressure on the side of the piston next to the said controlling element is greater than the pressure on the opposite side of the said piston.

4f. In a single chamber air pressure valve the combinationfof a train pipe, a casing, a piston working 1n such casing, a permanent connection from the train pipe to the casing, whereby one side of the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant torce on such piston in opposition to the train pipe air pressure, a brake control valve, and a controlling element operatively connected to the said piston and adapted to control the connection between the escape side of the said brake control valve and the atmosphere and simultaneously a connection between the two sides of the said piston, and a channel in the casing provided with an automatic valve adapted to open whenever the pressure on the side of the piston next to the said controlling.

element is greater than the pressure on the opposite side of the said piston the said channel in the casing ending in a nozzle on the side of the said piston opposite the said controlling element.

5. In a single chamber air pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing whereby one side of the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant force on such piston in opposition to the train pipe air pressure, a

slide valve connected to the said piston and provided with ports and channels, a seat for such slide valve likewise provided with ports and three main channels, one of the latter being permanently connected to the atmosphere, the second being permanently connected to the escape side of the brake control valve and the third main channel being permanently connected to the side of the said piston opposite to the slide valve, such slide valve being adapted to close and open the third of the said channels and at the same time to break and establish respectively the connection between the irst and the second of the said three channels in the 'said valve seat, a channel connecting ports on the opposite sides of the slide valve and additional channels in the slide valve seat connecting the main channel leading to the atmosphere and a pori; in the slide valve seat such port being located in the path of that of the said ports of the slide valve connected with each other by the said channel, which is in the sliding surface of the slide valve.

6. In a single chamber air'pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing whereby one side of the piston is constantly under the action ot the train pipe air pressure, means permanently acting with a substantially constant force on such piston in opposition to the train pipe air pressure, a slide valve connected to the said piston and provided with ports and channels, a seat for such slide valve likewise provided with ports and three main channels, one of the latter being permanently connected to the atmosphere, the second being permanently connected to the escape side of the brake control valve and the third main channel being permanently connected to the side of the said piston opposite to the slide valve, such slide valve being adapted to close and open the third of the said channels and at the same time to break and establish respectively the connection between the first and the second of the said three channels in the said valve seat, a further channel connecting parts of the opposite sides of the slide valve and a port in the slide valve seat permanently connected to the channel in the casing connecting the spaces on opposite sides of the piston, the last named port being in the path ot that of the two ports connected by the said further channel in the slide valve which is in the sliding surface of the slide valve and a partition in the slide valve adapted to cover, when the slide valve is in its extreme position under the action of the said substantially constant force, the said port of the slide valve seat which is permanently connected to the channel in the casing connecting the spaces on opposite sides of the said piston.

7. In a single chamber air pressure valve the combination oi a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing whereby one side of the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant force on such piston in opposition to the train pipe air pressure, a slide valve connected to the said piston and provided with ports and channels, a seat for such slide valve likewise provided with ports and three main channels, one of the latter being permanently connected to theatmosphere, the second being permanently connected to the escape side of the brake cont-rol valve and the third main channel being permanently connected to the side of the said piston opposite to the slide valve, such slide valve being adapted to close and open the third of the said channels and at the same time to break and establish respectively the connection between the first and the second of the said three channels in the said valve seat, and a further channel connecting parte on the opposite sides of the slide valve and a port in the slide valve seat permanently connected to the channel in the casing connecting' the spaces on opposite sides of the pis'on, the last named port being in the path of that of the two ports connected by the said further channel in the slide valve which is in the sliding surface of the slide valve and a partition in the slide valve adapted to cover, when the slide valve is in its extreme position under the action of the said substantially constant force, the said port ot the slide valve seat which is permanently connected to the channel in the casing connecting the spaces on opposite sides ot the said piston.

8. In a single chamber air pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing whereby one side oi the piston is constantly under the action oi' the train pipe air pressure, means permanently acting with a substantially constant force on Such piston in opposition to the train pipe air pressure, a slide valve connected to the said piston and provided with ports and channels, a seat for such slide valve likewise provided with ports and three main channels, one of the latter being permanently connected to the atmosphere, the second being permanently connected to the escape side ot the brake control valve and the third main channel being permanently connected to the side of the said piston opposite to the slide valve, such slide valve being adapted to close and open the third ot the said channels and at the same time to break and establish respectively the connection between the first and the second of the said three channels in the said valve seat, and a further channel connecting parts on the opposite sides of the slide valve and a port in the slide valve seat permanently connected to the channel in the casing connecting the spaces on opposite sides 0f the piston, the last named port being in the path ot' that of the two ports connected by the said further channel in the slide valve which is in the sliding surface of the slide valve and a partition in the slide valve adapted to cover, when the slide valve is in its extreme position under the action of the said substantially constant force, the said port of the slide valve seat which is permanently connected to the channel in the casing connecting the spaces on opposite sides of the said piston, a recess in the slide valve to opposite sides of which lead the said channel and further channel connecting ports on opposite sides of the slide valve, a piston rod secured to the said piston and a projection on such piston rod engaging with play the said recess and adapted to close that of the said channels which ends at the side of the said recess with which the said projection is n Contacto 9. In a single chamber air pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing, whereby one side of the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant force on such piston in opposition to the train'pipe air pressure. a brake control valve and a controlling element operatively connected to the said piston and adapted to control the connection between the escape side ot the said brake control valve and the atmosphere and simultaneously a connection between the two sidesv a oi' the said piston, and a second piston work,`

ing in a cylinder permanently connected with the brake cylinder, the rod of such second piston entering the casing and being adapted to push the piston in such casing into a predetermined position and to serve as a stop for the reverse movement of such piston.

l0. In a single chamber air pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing, whereby one side ot the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant force on such piston in opposition to the train pipe air pressure, a brake control valve, a slide valve connected to the said piston and provided with ports and channels` a seat for such slide valve likewise provided with ports and three channels, one of the latter being permanently connected to the atmosphere.y the second being permanently connected to the escape side ot the brake control valve and the third channel being permanently connected to the side ot the said piston opposite to the slide valve, such slide valve being adapted to close and open the third of the said channels and at the same time to break and establish respectively the connection between the first and the second ci the said three channels in the said slide valve seat and a second piston working in a cylinder permanently connected with the brake cylinder1 the rod of such second piston entering the casing and being adapted to push the piston in such casing together with the slide valve into the position in which all three of the said channels are closed and to serve as a stop for the reverse movement of such piston.

11. In a single chamber air pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing, whereby one side of the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant force on such piston in opposition to the train pipe air pressure, a

brake control valve and a controlling element operatively connected to the said piston and adapted to control the connectionv between the escape side of the said brake control valve and the atmosphere and simultaneously a connection between the two sides of the said piston, a valve controlling' a connection between the pipe leading` to the esca-pe side of the brake control valve and an opening leading into the atmosphere, and a spring tending' to keep such valve open.

12. In a single chamber air pressure valve the combination of a train pipe, a casing, a piston working in such casing, a permanent connection from the train pipe to the casing, whereby one side of the piston is constantly under the action of the train pipe air pressure, means permanently acting with a substantially constant force on such piston in 20 opposition to the train pipe air pressure, a

brake control valve and a controlling element operatively connected to the said piston and adapted to control the connection between the escape side of the said brake control valve and the atmosphere and simultaneously a connection between the two sides of the said piston, a valve controlling a connection between the pipe leading to the escape side of the brake control valve and an opening leadingV into the atmosphere, and a spring tending to keep such valve open and a double seat valve provided in Jfront of the first named valve in the said pipe, one of the seats of such double seat valve leading` to the space between the two valves and the other of such seats leading to the atmosphere.

In testimony whereof we have signed our names to this specication.

JOHANN RIHOSEK. RICHARD LUDWIG LEUCHTER. 

